package com.shujia.flink.tf

import org.apache.flink.api.common.functions.FlatMapFunction
import org.apache.flink.streaming.api.scala._
import org.apache.flink.util.Collector

object Demo3FlatMapFuncation {
  def main(args: Array[String]): Unit = {
    //创建flink环境
    val env: StreamExecutionEnvironment = StreamExecutionEnvironment.getExecutionEnvironment

    val linesDS: DataStream[String] = env.readTextFile("data/words.txt")

    //java api
    val wordsDS: DataStream[String] = linesDS.flatMap(new FlatMapFunction[String, String] {
      /**
       * flatMap： 一条数据执行一次，传入一条数据可以返回多条数据
       *
       * @param value ：一行数据
       * @param out   ：用于将数据发送到下游
       */
      override def flatMap(value: String, out: Collector[String]): Unit = {
        val split: Array[String] = value.split(",")
        for (word <- split) {
          //将数据发送到下游
          out.collect(word)
        }
      }
    })

    wordsDS.print()

    env.execute()
  }

}
